A thermoplastic resin is classified into a crystalline thermoplastic resin and an amorphous thermoplastic resin. A crystalline thermoplastic resin such as polyacetal and polyamide has not only excellent mechanical properties, heat resistance, electrical properties, and formability but also excellent sliding properties. Therefore, the crystalline thermoplastic resin is used in various fields as a sliding member such as a bearing and a gear.
However, in recent years, a high demand is being made for the sliding member along with development of the above-mentioned fields. In particular, sliding properties such as a friction coefficient, a wear amount, and sliding sound (squeaking sound) of the sliding member is desired to be further improved.
Meanwhile, an amorphous thermoplastic resin such as a polycarbonate resin and an acrylonitrile-butadiene-styrene copolymer (ABS) resin has an excellent heat resistance, resistance to shock, and dimensional stability. For that reason, the amorphous thermoplastic resin is used as a material of various parts of OA equipment or the like in an electrical and electronic field or an automobile field. However, the sliding properties of the amorphous thermoplastic resin are less than those of the crystalline thermoplastic resin. In this regard, attempts are being made to add or select an improving agent for giving a function of sliding properties or wear resistance to an amorphous thermoplastic resin having excellent dimensional stability.
A general technique for improving the sliding properties of a thermoplastic resin is disclosed in Patent Literature 1 to Patent Literature 4.
In the technique described in Patent Literature 1, a graft copolymer containing polyethylene or an ethylene-glycidyl methacrylate copolymer and acrylonitrile-styrene copolymer or polystyrene is used as an additive. In the technique described in Patent Literature 2, a multi-phase structure resin formed of an olefin-based copolymer and a vinyl-based copolymer is used as an additive.
In Patent Literature 3, a technology in which a hard coating layer is formed by coating and curing an ultraviolet curing acrylic hard coating agent on a surface of a finally-molded thermoplastic resin is disclosed.
Further, in Patent Literature 4, a technology in which a fluorine/silicone-based coating composition as a surface processing agent is coated on a surface of an ABS resin in order to suppress or reduce squeaking sound is disclosed.